Dangerous Deposit

Former President Gerald Ford, pictured here, was an avid skier. Do you like to ski? If you do, then you probably know that skiing can be a dangerous sport. Running into other skiers or trees is one risk. Avalanches are another.

Why It Matters

An avalanche is a sudden downhill rush of a large mass of snow. One of the biggest causes of avalanchesis surface hoar, or surface frost.

Surface hoar forms when water vapor in the air contacts cold surfaces and changes directly to ice crystals. This change of state is called deposition.

Surface hoar often forms on top of snow. If more snow falls on top of the frost, the frost forms a weak layer of ice crystals within the snowpack. This increases the risk of avalanches.

Why does it matter? You’ll see why when you watch the following video. It shows three expert skiers barely escaping from an avalanche in the Swiss Alps.